The Testosterone to Estradiol (E2) Ratio for Bodybuilders

The optimal proportion between free testosterone and estradiol is a subject of extensive discussion and debate within our community, and we haven’t really reached a definitive consensus.

Free Testosterone is particularly relevant because it is the form of Testosterone that is readily available to bond with various tissues, including muscles.

Unlike bound Testosterone (the difference between Total and Free Testosterone), which is constrained by Sex Hormone-Binding Globulin (SHBG), Free Testosterone can directly impact muscle growth and performance.

Estradiol, interestingly, also contributes to sex drive, muscle fiber growth, and muscle recovery after exercise, so it is not the devil that many people would want you to believe it is.

Having a good Free Testosterone to Estradiol ratio is the key to feeling good and having a healthy libido both on and off cycle, because having a bad ratio is what causes the typical side-effects like sexual dysfunction, gynecomastia, moodiness, and acne.

Ideal Test & E2 Ratio

In a bodybuilding and performance enhancement context, the IDEAL ratio of Free Testosterone to Estradiol should be around 5:1 off-cycle, and up to 10:1 on-cycle. In other words, for every unit of Estradiol, we want to have around 10 units of Free Testosterone.

This is where it gets complicated.

In the United States, Free Testosterone is typically measured in ng/dl (nanograms per deciliter), whereas Estradiol is measured in pg/ml (picograms per milliliter).

10 pg/ml =1 ng/dl

• Meaning that if our estradiol levels are 10 pg/ml, we need our Free Testosterone levels to be 1 x 10 = 10 ng/dl for the ratio to be 10:1. Same number, different units.

• Next time you get bloodwork done (off-cycle), chances are your estradiol levels will be in the 20 to 40 pg/ml range, and your Free Testosterone levels will be in the 10-20 ng/dl range. Meaning that if your estradiol levels are 20 pg/ml, a 10 ng/dl Free Testosterone level will be exactly a 5:1 ratio.

• If you get tested on-cycle, you want your Estradiol to remain in the 20 to 40 pg/ml range, and your Free Testosterone to be in the 20 to 40 ng/dl range, ideally at the same number for the ratio to be 10:1.

Note that if you’re outside the US your bloodwork results may be in the same measurement unit, so all you’ll have to do is divide the Free Testosterone levels with the Estradiol levels.

Example:

• Free Testosterone 200 pg/ml
• Estradiol 40 pg/ml
• 200/40 = 5 (5:1 ratio)

Considerations

As you can imagine, nailing this ratio is extremely difficult, even if you are getting bloodwork done often and you use chemistry to regulate your Estradiol and Free Testosterone levels, hence why we call it “ideal”.

There is no need to be obsessive about it: Having a ratio anywhere between 5:1 and 10:1 is great, whether you are on or off-cycle. What you want to prevent is your ratio from falling below 5:1, because the lower it goes, the more likely you are to get estrogenic side-effects like gynecomastia, acne, moodiness, etc…

One of the main things that swayed me off PEDs for a very long time was my OCD around having everything perfectly; unfortunately, the truth is that your body is best at regulating everything on it’s own. And when you take that into your own hands by introducing PEDs, sh*t happens.